Extension-ladder



(No Model.) I 0. A. STAPLES.

EXTENSION LADDER.

No. 368,737. Patented Aug. 23, 1887.

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ITED STATES PATENT rricn.

EXTENSION-LADDER.

$PECIFICATION forming part of Letters Patent No. 368,737, dated August23, 1887. Application filed April 2, 1886. Serial No. 197,502. (Nomodel.)

To all whom it may concern.-

Be it known that I, CHARLES A. STAPLES, of Cambridge, in the county ofMiddlesex and State of Massachusetts, have invented a new and usefulImprovement in Extension- Ladders, which will, in connection with theaccompanying drawings, be hereinafter fully described, and specificallydefined in the appended claim.

Figure 1 is a perspective view of. a ladder embodying my invention, aportion at each end being broken away. Fig. 2 is a transverse sectiontaken on line Z, Fig. 1. Fig. 3 is adetached view showing the relationof parts when the ladder is being raised. Fig. 4 is a view similar toFig. 3, except that the parts are shown as when the ladder is beinglowered. Fig. 5 is a view like Fig. 4,.except that the pawl is shown asprovided with a helical spring in lieu of an arm-spring for tilting it.Fig. 6 is a view like Figs. 4, 5, except that the pawl is shown asprovided with a weight instead of a spring .for tilting it.

The object of my invention is to provide an extension-ladder withsupports or pawls that will automatically engage the rungs of the loweror stationary section when the upper or sliding section is being raised,and so support the upper section when raised to the desired height, andwhich will disengage themselves from the rungs of the lower section whenthe upper section is being lowered; and these results I accomplish bymeans hereinafter fully described in connection with the accompanyingdrawings.

In said drawings, A A represent the standards or side bars of the loweror stationary section of the ladder, the same being united by rungs a inthe usual manner, as shown. The side bars of the upper or adjustablesection are shown at B B, and are united by the rungs b, as shown. Theseupper and lower sections are in the usual manner formed with suchrelative widths that the upper section fits and slides freely within theside bars of the lower section, sliding upon the rungs a and checks 6,and the sections are at the upper end secured together by the clamp orbar 0, which embraces the upper section, and at its ends" is secured tobars A A, while the clamps d d secure the lower end of bars B relativelyto the lower section, the chocks 6 being of equal thickness with bars A,as shown; but the method of securing the sections together constitutesno part of my invention.

rm v l The upper or sliding section is raised and lowered by means ofrope f, passing over sheave 9, supported in vertical bar h, secured torungs 6b of the lower section; but said means of raising and loweringthe upper section constitute no part of my invention and may besubstituted by other well-known means.

For the purpose of supporting the upper section at the desired height, Ihave invented the pawl 71, having the short arm I and longer arm m, andthe seat It between said arms to receive the rungs a. One of said pawlsis pivoted to each standard B at j, and is pro vided-with an arm spring,a, secured at I to the standard, and is provided with a fulcrum, q, sothat the spring tends constantly to force the pawls inward to theposition shown in dotted lines in Fig. 4, thus insuring their cont-actwith each rung a in passing it. Therefore, when the sliding section israised, as soon as arm Z of the pawls is above a rung in the lowersection the action of spring a will bring arm in against the rung, asshown in Fig. 6, when, by slightly lowering the upper section, the pawlwill be seated upon the rung, as shown in Figs. 1 and 3, and the uppersection thereby supported. To lower the upper section it is onlynecessary to raise the upper section till arm or is above the rungengaged by the pawls, when they assume the position shown by dottedlines in Fig. 4, when the section may be lowered,

the pawls in passing rungs a assuming the.

position shown in Figs. 4, 5. Instead of an armspring, n, a helicalspring, 8, as shown in Fig. 5, or a weight, if, rigidly secured to orformed upon the pawls, may be employed to tilt the same out of contactwith rungs a when the upper section descends.

I claim as my invention In combination with sections A B of anextension-ladder, the pawls t, pivoted on section B, and formed withlonger arm, m, and shorter arm, Z, parallel, or nearly so, with eachother, with open seat It, arranged'to serve as a thrustsupport ofsection B, and means, substantially as described, whereby said pawls areheld in the line of and are engaged with rungs a, substantially asspecified.

CHARLES A. STAPLES.

Witnesses:

T. W. PORTER, O. W. H. MOULTON.

